Benchmarked strictly across TripTiming's 5 empirical pillars: Crowds, Weather, Vibes, Prices, and Safety.
Porto emerges as the optimal May destination with an overall TripTiming Index of 66/100 vs 64/100 for Lisbon (+2 point advantage). Porto experiences substantially lower visitor footfall and shorter landmark queues (heavy visitor congestion vs peak seasonal crowding in Lisbon). This is reinforced by lower lodging rates (~$248/night vs ~$307/night, saving ~$413 over 7 nights). While Lisbon retains an edge in Weather Comfort (99/100 vs 82/100), Porto's commanding performance in Space & Crowds secures the overall May recommendation.